16 GEOLOGY. 



Mourne Mountains, the Slieve Croob and Slieve Gullion region, and the 

 Carlingford division. On the N. and E. are Silurian slates highly- 

 altered where in contact with the granite ; on the S. the granites are 

 surrounded by Carboniferous Limestone ; and the whole district is freely 

 penetrated by trap-dykes. The anorthite-syenite resembles the hyper- 

 sthene- syenite of Skye, except in the lime-felspar being anorthite, not 

 labradorite ; and the author considers that it and the granite of the 

 same district are practically contemporaneous, as each sends veins into 

 the other, and that some of the syenites may be altered granites. Gra- 

 nite in a imstj condition coming in contact with a mass of limestone, 

 and some peroxide of iron, would be fluxed into a syenite like that of 

 Carlingford Mountain. 



The mineralogical compositions of igneous rocks may be mathemati- 

 cally determined according to the Law of Least Paste (an application 

 of the Law of Least Action), the same having been adopted in the eluci- 

 dation of the mineral percentages of the lavas of Vesuvius (see post, 

 Petkology) ; and an example is given of the syenite of Grange Irish, 

 Carlingford. 18 analyses of the trap-rocks and syenites are given. 



E. T. H. 



Heathcote, J. M. Reminiscences of Fen and Mere. 8vo. London. 

 Notices the geology of the Eens. 



Hicks, Henry. The Oldest Eossiliferous Eocks of Northern Europe. 

 Geol. Mag. dec. ii. vol. iii. pp. 240, 379, 380. 



Insists on the depression of the British before the Swedish area in 

 Cambrian and Silurian times, and on the difference of the Harlech and 

 Menevian faunas. 



Tabulates the Welsh Cambrian Series, correlating the Swedish Para- 

 doxides Schists with the Menevian. W. H. D. 



Llandovery Eocks in the Lake-District. Geol. Mag. dec. ii. 



vol. iii. pp. 335, 336, 429, 430. 



The Coniston Mudstones, Elags, and Grits = U. and L. Llandovery= 

 Tarannon Shales and Denbighshire Grit. Oscillations and denudation 

 during deposition produced the unconformities. 



The Coniston Mudstone fossils are mostly U. Bala and L. Llandovery. 

 The Tarannon Shales = L. Llandovery : they had no known fauna when 

 mapped by the Geological Survey. W. H. D. 



. On some Areas where the Cambrian and Silurian Eocks occur 



as Conformable Series. Rep. Brit. Assoc, for 1875, Sections, p. 69. 



The succession is complete and unbroken in Pembrokeshire, near 



Llandovery, in parts of Shropshire, and probably near Corwen. These 



areas received deposits uninterruptedly from the commencement of the 



Cambrian to the close of the Silurian. ^ W. T. 



. On " Dimetian and Pebidian" Beds. Land and Water, 



vol. xxii. no. 570, p. 465. 

 States that these are sedimentary rock older than the Cambrians of 



